As methods of producing fatty acid alkyl esters by ester exchange between triglyceride-based fats/oils and lower alcohols, various methods are known. This reaction for example in JP-A56-65097 is allowed to proceed with an alkali catalyst while glycerin formed by multistage reaction is separated. However, a homogeneous catalyst is used therein thus necessitating a step of neutralization/removal of the catalyst after the ester-exchange reaction, to make a glycerin purification process complicated.
To solve this problem, WO-A05/021697 has reported a process for producing fatty acid alkyl esters by using a solid acid catalyst.